Field of the Invention
The present invention relates to an image capturing apparatus, an image capturing method, and a control method.
Description of the Related Art
When shooting photographs under artificial light sources that flicker, the amount of light is low, and it has thus been impossible to shoot photographs at higher shutter speeds. As such, exposure unevenness caused by flicker has thus far not posed a very serious problem. However, recent years have seen higher ISO capabilities in digital cameras, which has made it possible to shoot at high shutter speeds even under artificial light sources that flicker. When continuous shots are taken at a high shutter speed under a flickering light source, the exposure amount will vary from frame to frame due to changes in the amount of external light.
In light of this problem, Japanese Patent Laid-Open No. 2006-222935 proposes a technique that detects flicker in illumination light, and in the case where an exposure time is shorter than the cycle of the flicker, adjusts the timing at which an image is captured so that the center of the exposure time essentially matches the timing at which the illumination light is at a maximum value.
However, according to the technique disclosed in Japanese Patent Laid-Open No. 2006-222935, the flicker is detected using a dedicated microcomputer and photoelectric conversion element for flicker detection. Although detecting flicker using a photoelectric conversion element (an image sensor) for capturing images can be considered, live view operation, in which images captured by the photoelectric conversion element for capturing images are displayed continuously in a display apparatus, typically displays an image in which exposure unevenness caused by flicker is suppressed. It is difficult to detect the timing at which the amount of illumination light is at a maximum value from an image in which exposure unevenness caused by flicker has been suppressed, and thus the influence of the flicker on still image exposure cannot be reduced.